Preheat the oven to 375°F.
In a small saucepan, melt the butter over low heat, then stir in minced garlic, pickle seasoning, and pickle juice. Set aside.
Grease the bottom of a 9x13-inch baking dish with a thin layer of the garlic pickle butter mixture.
Slice the slider rolls horizontally, keeping them connected, creating top and bottom layers. Place the bottom layer in the prepared dish.
Mix the mayonnaise and Dijon mustard, then spread evenly on the inside of the top half of the rolls.
Layer ham, Swiss cheese, and pickle slices evenly over the bottom half of the rolls, then place the top half over the fillings.
Brush the remaining garlic pickle butter generously over the tops of the rolls and sprinkle with poppy seeds if desired.
Cover the baking dish with aluminum foil and bake for 10 minutes.
Remove the foil and bake for an additional 5 to 7 minutes until the tops are golden and cheese is melted.
Sprinkle chopped fresh parsley over the sliders, let cool slightly, then slice and serve.